x_max = 2*pi;
N = 64;
k = 0.1;
u = initial_data(N,x_max);
u0 = u;
u = trapezoidal(u,N,x_max,k,10);
u1 = u;
u = trapezoidal(u,N,x_max,k,10);
u2 = u;
u = trapezoidal(u,N,x_max,k,20);
u3 = u;
plot_fig(x_max,N,u0,u1,u2,u3);
